Lots of good advice on here, so I'm just going to add my experience:
I met my current (and wonderful and supportive) boyfriend online. I didn't say anything in my profile about my diet because I don't want to be defined by Celiac or stereotyped by the name of a fad diet. I did mention that I love cooking and baking from scratch. I'd meet people for coffee - that's my general rule. That way 1) I wouldn't have to worry about picking a restaurant and 2) if it wasn't going well I could cut the date somewhat short and not feel obligated to stick around for hours on a bad date, lol.
I would casually bring up my diet when it came up naturally in conversation. Most guys were actually really accepting of it and wanted to know more about it. I always spoke about my diet in the most positive way. You'd be surprised how many understanding guys there are out there, even ones who know what Celiac is or have a family member/friend who has it.
My boyfriend had an old roommate with Celiac so he knew a lot about CC. He realized the issue with kissing on his own and said "Oh! I'll just brush my teeth!"
Have confidence in yourself and don't feel like you are hiding anything. Everyone has foods they prefer not to eat and there are SOOO many people out there with other allergies or food intolerance. If a given guy turns out to be rude or unaccepting about it, then you wouldn't want to be with him anyway!